PDF glossary
Signature verification
Checking that a PDF’s digital signature is valid, who signed it and when, and whether the document changed afterwards.
Verifying recomputes the digest of the covered bytes, checks the signature with the public key in the certificate, and looks at whether anything was added after the signature.
A signature can be valid and still be followed by later changes — a counter-signature, or an edit — which a good verifier reports separately.
In PDF-SDK
Each signature comes back with its signer, time and reason, whether it is valid, whether it covers the whole file, its certification level and a one-line summary.
Verify PDF signaturesLast reviewed